Power control for a pneumatic tube carrier system



Sept. 18, 1934. GROVER 1,973,954

POWER CONTROL FOR A PNEUMATIC TUBE CARRIER SYSTEM Filed Oct. 19, 1933 INVENTOR. CZ/mnvn M 5/90 up.

A ITORNEYJ.

Patented Sept. 18, 1934 UNITED STATES POWER CONTROL FOR A PNEUMATIC TUBE CARRIER SYSTEM Clarence W. Grover, Highland Park,- Mich., as-

Sig or toGrover Company, Detroit, Mich a corporationof Michigan Application October 19,

10 Claims.

This invention relates to a power control for a pneumatic tube carrier system, This invention relates more particularly to a power control for a pneumatic tube carrier system of the minimum fi'ow type. The minimum new type carrier system is old and well-known, and is characterized by the fact that a small flowoi air is at all times maintained through the system and that the maximum power is obtained upon the introduction of a carrier into the tube through a power control device which throws on the full power which drives the carrier through the system. After the carrier reaches" its destination and is discharged the full power must be turned off and the minimum flow again restored. This invention relates particularly to that portion of the power control apparatus which reduces the full power widow of air to the minimum power or flow as soon as the carrier reaches its destination or whenever the velocity of the carrier exceeds an arbitrary or desirable maximum;

It is also broadly old' in the" art to reduce the system from a'i'ull power status to a minimum power or minimum flow status by utilizing the increased velocity or kinetic energy oi? the air flowing; through the tube broughtabout by the discharge of. the carrier.. It is an object of this invention to produce an improved type of power control which is actuated by the increased ,velocity of the air flow caused by the removal of the load, that'is', the discharge of thecarrier from the tube, which is quick acting,.reliab1e, simple, durable, and. appreciably cheaper to manufacture than any power control whi'chhas heretofore been suggested or placed upon the market.

In the drawing:

Figure 1' is al'ay-out of a conventional form of pneumatic tube carrier system, 7

Figure-2 isa' vertical sectionthrough the power control when the system is inoperative" and a minimum flow of air maintained. I

Figure 3 is a vertical section through the power control showing the position of the various parts immediately subsequent to the discharge of the carrier and as the balanced val-'ves are about to close. p Figured is a section along the lined-4' of Figure 3'. I Referring to Figure 1' there is shown a conventional form of pneumatic tube carrier system comprising a vacuum tank'l, power control'2, and stations 3 and 4 which are connected bythepower tubes 5 and 6. It is understood, of course, that whether the system is operated by pressure or 1933, Serial No, ($4,233 (CL 243-42 suction, the apparatus functions the same and one is the equivalent of the other. The'air flow is from station 3 through pipe 5 to station 4, and from station ,4 through pipe 6 back to station 3 and then through the control 2 to the vacuum tank 1, The power control 2' ispositioned be tween the vacuum tank land the return tube-ca Hence, referring to Figure 2 the'inlet port of the control maybe designated '7' and the outlet port, which leads to the vacuum tank, designated 8.

The power control comprises a casing which encompasses a main air chamber 11. The main casing" 10' is provided with an auxiliary casingrz which in turn encompasses the outlet chamber 13. The casing 12' is provided with the outlet ports 14 and 15 which are controlled by the valves 16' and 1'7 respectively. The valves loan-d- 1? are known as balanced valves, that is, the valve 16 is on the windward side of the port l4 whereas the valve 17 is on the leeward side of the port I5. In other words", the valve 16' is without the outlet chamber 13 and the valve l7 is within the chamber 13. Thus, when the valves are" either opened or closed the; pressure ontthe valve 16 tending to close, or to hold closed, the valve 16 counterbalances the pressure on the vaivexr'r tending to open, or to hold open, the valve 17"; The valves l6 and 1'7 are mounted in spaced refer-- tion upon the sleeve 18 which in turn is slidabl'y mounted upon the shaft 19. One end of the shaft 19 is journaled in the adjusting screw 20 which is threaded in the opening 21in one Wall of the casing I0. The screw, 20 is providedwith anv annular collar 22 and adjusts the tension of the coil spring 23 which is mountedbetween the valve 16'- and the collar"22., The other end of the shaft is threaded into" the spider 24 which extends across the opening 25' in'th'e'j opposite wall of the casing 10". y "l 'I-he valves 1 6 and 17 maybe" contro1ledany suitable type of pneumatic. Y By' way or? description the opening 25 in the "wan: of the casingio is closed by a pneumatic which herein-takest'li form ofa flexible leather diaphra'ghiZEi which is secured to an end of thesleeve 1 8fby'tlie op posed nuts 27 and 2s threaded over the s1eeve 18. Preferably the adjust'ingscrew 2'0'is1adtuste d so that the maximum force" of the c'oil spring 23 when collapsed is slightly less than empowe of the diaphragm 216' createdby the" difference iii pressure between the inside'and the outside of the casing IOwheh the balanced valves are throtvl-iopen and full power is applied'totubes- 5* and 6 Since this power control device'-is'- adapted for use in a' pneumatic tube carrier system of" the sliding fit with the sleeve 13.

minimum flow type, such minimum flow may be obtained in any of the well-known ways as by providing the inner casing 12 with a small outlet port 29 and a screw valve with a conical end for regulating the amount of air permitted to flow through the opening 29.

The operation of the power control'is as'follows: Assuming the balanced valves 16 and 1'7 are in closed position, as shown in Figure 2, and

a minimum flow of air, as permitted by the port 29 and regulating valve 30, is flowing through the tubes 5 and 6 and inlet '7 into the casing 10 and through the port 29 to the chamber 13 and thence through the outlet 8 to the vacuum tank 1. If a carrier is now placed in the inlet end of the tube 5, this carrier serves as a piston and blocks the flow of atmospheric air into;the tube 5. Hence, the pressure is gradually decreased in the chamber 11, that is, the amount of vacuum in creases and in a Very short time outside atmosphericpres'sure on the diaphragm 26 becomes sufficiently greater than the pressure in the chamber 11 plus the force of the coil spring 23 to move the sleeve 18 with the valves 16 and 1'? toward the left, or to open position, upon the guide 19, as shown in Figure 3. At this time, since ports 14 and 15 are now open, a maximum flow of air through the power control is permitted and the full power or suction is applied to the carrier thus drawing the same through the tube 5 until discharged through the hinged valve outlet of the tube 5 at the station 4. At this time the valves 16 and 17 are still open and a full flow of air is passing through the tubes 5 and6, through the control 2 into the tank 1 thus causing a waste of power. Hence, it is desirable that the valves16 and 17 be thrown to closed position as soon as the carrier is discharged.

To this end the casing 10 is provided with a guide rod 31, one end of which is journaled' in the adjusting screw 33. The guide rod 31 has slidably mounted thereon the slide 34. A coil spring 35 is threaded over the rod 31 between the inner end of the adjusting screw 33 and the with an embossed opening 38 which has'a nice The tension of the spring 35 can be adjusted by the screw33 so that the force exerted against the slide 34 is sufficient to hold the slide with its vane 36 and valve 37 in the open position shown inFigure 2 atall times, except when the velocity of the air through the inlet opening 7 is increased beyond the normal rate of flow, Such increase in velocityoccurs when the carrier is discharged,

, or when the speed of the carrier in the tube exceeds a predetermined rate as, for instance, when the carrier drops where'the tube extends vertically an appreciable distance. I V

The guide rod 31 is threaded at one end and provided with an adjusting nut 39 which can be adjusted back and forth along the rod '31 to valve 3'? when open the air striking the inclined vane 36 forces the slide 34 to the left compressing the coil spring 35 and moving the valve 37 to the position shown in Figure 3 so that it closes the port 15. Since the pressure in the vacuum tank 1, which is less than atmospheric pressure, is constant, as soon as the'port 15 is closed the velocity of the-flow of air through the port 14 is increased which in turn increases the closing force against the valve Further, as above explained, when the balanced valves 16 and 17 are open the force of the collapsed coil spring 23 plus the pressure in the chamber 11 is but slightly less than the atmospheric pressure upon the diaphragm 26. Then too, before the valve 37 is thrown to closed position, the pressure of the air flowing through the inlet 15 exerted against the valve 1'7 and tending to hold the same open is about equal to the pressure of the air flowing through the opening 14 exerted against the valve 16 and tending to close the valve 16. Hence, as soon as the valve 37 closes the port 15, owing to the force exerted against the vane 36 caused by the increased velocity of the air uponthe discharge of the carrier, this pressure upon the valve 17 which tends to hold the valve open is now removed thus throwing the balanced valves out of balance. This cutting off of the pressure on the valve 17 and the additional closing force which is exerted on valve 16 by the speeding-up of the air flowing through the port 14, throw the valves 16 and 17 out of balance and they move to closed position as shown inFigure 2.

As soon as the valves 16 and 17 close the ports 14 and 15, the flow of air through the tubes 5 and '6 and the inlet '7 is reduced to the minimum flow, and since the speed of the air is greatly decreased, the force now exerted upon the vane 36 is less than the force of the coil spring 35 whereupon the slide 34, vane 36 and valve 37 are moved to the right or to open position thus placing the vane in the position shown in Figure 2 ready for operation as soon as another carrier is discharged from the tube.

It is, of course, understood that the entire action of this power control is almost instantaneous and encompasses at most but a very few seconds.

It is evident from the above description that there is herein shown a power control for a pneumatic tube carrier systemof the balanced valve type utilizing the increased speed of the air flow immediately following the removal of the load or discharge of the carrier from the tube which is characterized in that the speeded up air flow causes an auxiliary valve to close one of the air ports thereby throwing out of balance the various forces acting'upon the valves so that the closing forces exceed the opening forces and thus cause the valves; to close.

What is claimed is:

1. A power control for a pneumatic dispatch system of the minimum flow type having a transmission conduit and a power source for creating a propelling air current through the conduit, comprising a pair of ports permitting air flow between the conduit and the power source, a pair of balanced valves" for controlling the ports, and auxiliary valve means normally open as when a carrier is being transmitted through the conduit or when' a minimum flow of air is permitted, said means being actuatable to close one of said ports by an increased flow of air through the conduit such as occurs when the balanced valves are open and the carrier is discharged'whereby the valves igccacsa are thrown out of: balance and moved to closed position; j H 2: A power control for' a pneumaticdispatch systemic? the minimum: flow typehaving a transmission conduit and a power source for creating a propelling-air current through the conduit, comprising-anfouter casing andan inner casing, a of ports permitting communication between the outer andthe inner casings; a pair of balanced valves for closing the said-ports; one of said valves being positioned withinthe outci casing and the other of said valves being position'ed" within the inner" casing, andauxiliary valve means. for. controlling one of said ports normally open as when'acarrieris being transmitted through'the conduitor when a minimum iiowof airis' permittedand actuata-ble'to close one of saidiports by an increased how of air through the conduit such 'as occurs when the balanced valves'are open and the carrier is. discharged whereby tlievalves are thrown out of balance and moved to closed position. 7

3., A power control for a pneumatic dispatch system offthe minimum flow type havinga transmission conduit and a. power source for creating av propelling air current through thelconduit', comprising aniouter, casingand an inner casing, a pair of ports permitting communication between theouteigandthe inner casingsa pairof balanced valves'forclhsiiig 'the said ports, one of saidvalves being positioned'withinithe outer casing and the other oi said valves. being positioned within the inner casing, an auxiliary valve for controlling oneoil saidlports, and avane actuatable by an in'- creased flow of. air through the conduit such as occurs when the. carrier is discharged for closing the said auxiliary valve whereby the balanced valvesare thrown out. of. balance and moved to closed position,

4.. A power control. for. controlling the new of air. between the transmission co'fiduit and the powen source of pneumatic dispatch systemof the minimumflow. type, comprising in combinae tion a pair otponts between. thepower source and the conduit ,a-pairot balanced valves for the said ports, a pneumatic exposed on one side to atmospheric pressure and on the other side to the pressure obtaining in the conduit, said pneumatic being operatively connected to the valves for opening the same upon the introduction or a carrier into the transmission conduit, resilient means for counterbalancing the said pneumatic, one of said balanced valves being on the leeward side of its port and the other being on the windward side of its port, an auxiliary valve for one of said ports normally in open position as when a carrier is being transmitted through the conduit or a minimum flow of air is permitted through the conduit, and means for closing said valve actuatable by an increased flow of air through the conduit such as occurs when the carrier is discharged from the conduit whereby the balanced valves are thrown out of balance and moved to closed position thereby cutting off the full flow of air.

5. A power control for controlling the flow of air between the transmission conduit and the power source of a pneumatic dispatch system of the minimum flow type comprising in combination a pair of ports between the power source and the conduit, a pair of balanced valves for the port, one of said valves being on the leeward side of the first port and the other being on the windward side of the second port, a pneumatic exposcd on oneside toatmosphericpressure and; on the other sidetothepressure obtaining iiithecon duit; said pneumatic being operatively connected to the valves for opening the same upon the in.- troduction of thecarrierinto its transmission conduit; resilient means for counterbalancing the said pneinnatic-, 'auxiliar-y valve means on the windward sideof the-first port normally inopen position as When a carrier is being transmitted through theconduit or a minimum flow oiai'r permitted through the conduit; said auxil'iary valvem'eans'being actuatable toolbse-thefirst of saidpc'rts by-a'ni'ncre'asedfiow 01- air through the conduit such occurs when the carrier is discharged from the conduit whereby the balanced valves are t'hrovvir outfofbalance and moved to clofsedposition thereby cutting on the full flow of air;

" 61A power controrfor controlling the fiow of air between. the transmission conduit and the power source of a pneumatic dispatch system of the; minimum flow type comprising in combina tion a pair of' ports between the' power source and" the conduit; a pair of balancedvalves for the ports; one of said. vaives-beingon the leeward side of the first port and the other b'eingonthe Windward side of thesecond port, a pneumatic having one face. exposedto atmospheric pressure andthe other to the pressure obtaining within the conduit; said pneumatic being operatively connected to the valves for opening the same upon'the introductibhflof th carrier into its transmission conduit,v resilient means for counterbalancing' the said pneumatic; an auxiliary valve positioned' on thewindward side of the first no part normally? in open position as when-a carrier being transmitted through the conduit or a minimum flow of air is permitted through the conduit; and vanemeans operatively connected to the said valve actuatable byan increased flow of" air through the conduit such as occurs when the" carrierisdischargedfrom the conduit to close said valve" whereby the balancedvalves are thrown out: ofbalance and moved to closed position. t

'T. A powercontrol for-controlling-theflowof between the transmission conduit and the power source of a pneumatic dispatch system of the minimum flow type comprising in combination a pair of ports between the power source and the conduit, a pair of balanced valves for the said ports, a pneumatic exposed on one side to atmospheric pressure and on the other side to the pressure obtaining in the conduit, said pneumatic being operatively connected to the valves for opening the same upon the introduction of a carrier into the transmission conduit, resilient means for counterbalancing the said pneumatic, one of said balanced valves being on the leeward side of its port and the other being on the windward side of its port, an auxiliary valve for one of said ports normally in open position as when a carrier is being transmitted through the conduit or a minimum flow of air is permitted through the conduit, and means for closing said valve actuatable by an increased flow of air through the conduit such as occurs when the carrier is discharged from the conduit whereby the balanced valves are thrownout of balance and moved to closed position thereby cutting off the full flow of air, and means for returning the auxiliary valve and aforementioned actuating means to their normal open position as soon as the balanced valves are closed.

8. A power control. for controlling the flow of air. between the transmission conduit and the power source of a pneumatic dispatch system of the minimum flow type comprising in combination a pair ofports between the power source and the conduit, a pair of balanced valves for the said ports, one of said valves being on the leeward side of thefirst portandthe other being on the windward side of the second port, a pneumatic exposed on one, side to atmospheric pressure and on the other sideto the pressure obtaining in the conduit, said pneumatic being operatively connected to the valves for opening the same upon the introduction ofthe carrier into the transmission conduit, resilient means for counterbalancing the said pneumatic, an auxiliary valve on the windward side of the first port normally in open position as when a carrier is being transmitted through the conduit or a minimum flow of this permitted through the conduit, and a movable vanelinclined relative to the direction of the flow of air through the conduit operatively connected to the auxiliary valve and actuatable by an increased flow of air through the conduit such as occurs when the carrier is discharged from the conduit to close the first port whereby the balanced valves are thrown out of balance and moved to closed position.

9.;A power control for controlling the flow of air between the transmission conduit and the power source of a pneumatic dispatch system of the minimum fiow typecomprising in combination a pair of ports between the power source and the conduit, a pair of balanced valves for the said ports, one of said valves being on the leeward side of the first port and the other being on the windward side of the second port, a pneumatic exposed on one side to atmospheric pressure and on the other side to the pressure obtaining in the conduit, said pneumatic being operatively connectedto the valves for opening the sameupon the introduction of the carrier into the transmission conduit, resilient means for counterbalancing the'said pneumatic, an auxiliary valve on the windward side of the first port normally inopen position as when a carrier is being transmitted through the conduit or a minimum flow of air is permitted through the conduit, a guide support for the said auxiliary valve, an inclined vane guided onthe said support and operatively connected to thesaid auxiliary valve, the said inclined vane being actuatable by an increased flow of air through the conduit such as occurs when the carrier is discharged from the conduit to close the said auxiliary valve whereby the balanced valves are thrown out of balance and moved tov closed position thereby cutting off the full flow of air.

10. A power control for controlling the flow of air between the transmission conduit and the power source of a pneumatic dispatch system of the minimum flow type comprisingin combination a pair of ports between the power source and the conduit, a pair of balanced valves for the said ports, one of said valves being on the leeward side of the first port and the other being on the windward side of the second port, a pneumatic exposed on one side to atmospheric pressure and on the other side to the pressure obtaining in the conduit, said pneumatic being operatively connected to the valves for opening the same upon the introductio'nof the carrier into the transmission conduit, resilient means for counterbalancing the said pneumatic, an auxiliary valve on the windward side of the first port normally in open position as when a carrier is being transmitted through the conduit or a minimum flow of air is permitted through the conduit, a guide support for the said auxiliary valve, an inclined vane guided on the said support and operatively connected to the said aux+ iliary valve, the said inclined vane being actuatable by an increased flow of air through the conduit such as occurs when the carrier is discharged from the conduit to close the said auxiliary valve whereby the balanced valves are'thrown out of balance and moved to closed position thereby cutting off the full flow of air, and resilient means for returning the said auxiliary valve and vane to their initial normal open position as soon as the said balanced valves are closed.

CLARENCE W. GROVER.

led 

